Chemical Tests!!! Flashcards
What is the chemical test for hydrogen?
Lit splint –> Squeaky pop!
(Combustion of hydrogen causes the test tube to resonate)
What is the chemical test for carbon dioxide?
Limewater –> Turns cloudy
(Carbon dioxide reacts with limewater to make an insoluble white solid)
What is the chemical test for oxygen?
Glowing splint –> relights
(Oxygen allows wood to combust more efficiently)
What is the chemical test for ammonia?
Damp red litmus paper –> turns blue
(Ammonia reacts with dampness to form OH- ions)
What is the chemical test for chlorine?
Damp blue litmus paper –> turns white
(Chlorine is a bleaching agent, and removes colour from the paper)
How do you carry out a flame test?
1) Dip a piece of platinum wire into hydrochloric acid
2) Dip the wire into a sample of solid or solution
3) Place the tip of the wire into a non-luminous bunsen flame
What colour is formed in a lithium flame test?
Red
What colour is formed in a sodium flame test?
Yellow
What colour is formed in a potassium flame test?
Lilac
What colour is formed in a calcium flame test?
Orange-red
What colour is formed in a copper flame test?
Blue-green
How do you carry out a sodium hydroxide test?
1) Dissolve sample in water
2) Add a few drops of NaOH
What precipitate is formed in a sodium hydroxide test with copper?
Blue, Cu(OH)2
What precipitate is formed in a sodium hydroxide test with iron (Fe2+)?
Green, Fe(OH)2
What precipitate is formed in a sodium hydroxide test with iron (Fe3+)?
Brown, (Fe(OH)3
How do you carry out an ammonium test?
1) Dissolve the sample in water
2) Add some Na(OH) and warm it
3) Test the gas evolved with damp red litmus paper
What colour will the litmus paper turn is ammonium is present in ammonium test?
Blue
What is formed when ammonium reacts with sodium hydroxide?
A gas is formed
How do we test for halide ions (Cl-, Br-, I-)?
Silver Nitrate Test
How do we carry out the silver nitrate test?
1) Dissolve the sample in water
2) Add nitric acid
3) Add silver nitrate (AgNO3) solution
What precipitate forms when chlorine reacts with silver nitrate?
White precipitate, AgCl
What precipitate forms when bromine reacts with silver nitrate?
Cream, AgBr
What precipitate forms when iodine reacts with silver nitrate?
Yellow, AgI
How do we test for carbonates?
1) Add hydrochloric acid, look for effervescence
2) If there is effervesces, bubble gas through limewater
